A hydraulic valve timing controller controls valve timing of an intake/exhaust valve of an internal combustion engine by discharging operation oil from one chamber in a housing and by supplying operation oil to the other chamber in the housing to relatively rotate a vane rotor. JP 2013-151923 A (corresponding to US 2013/0192551 A1) describes a valve timing controller in which operation oil is supplied and discharged by an oil passage directional control valve disposed at the central part of the vane rotor. The oil passage directional control valve has a valve body with a based cylindrical shape and a spool movable in an axial direction inside the valve body. A drain space is defined by the spool and the valve body. The operation oil of oil pressure chamber is discharged through the drain port of the valve body to a drain oil passage including the drain space.
In recent years, it is required to raise the control speed of valve timing to raise the performance of internal combustion engine. In JP 2013-151923 A, a check valve is disposed in a supply oil passage to restrict the operation oil from flowing backwards from the oil pressure chamber to the supply oil passage. Moreover, in order to flow a large amount of the operation oil, an annular groove is defined on the inner side of each port of the valve body, such that the port open area is increased relative to a stroke of the spool.